Require Complex Calculations Research Articles

Nested CNN architecture for three-dimensional dose distribution prediction in tomotherapy for prostate cancer.

The hypothesis of changing network layers to increase the accuracy of dose distribution prediction, instead of expanding their dimensions, which requires complex calculations, has been considered in our study. Atotal of 137 prostate cancer patients treated with the tomotherapy technique were categorized as 80% training and validating as well as 20% testing for the nested UNet and UNet architectures. Mean absolute error (MAE) was used to measure the dosimetry indices of dose-volume histograms (DVHs), and geometry indices, including the structural similarity index measure (SSIM), dice similarity coefficient (DSC), and Jaccard similarity coefficient (JSC), were used to evaluate the isodose volume (IV) similarity prediction. To verify a statistically significant difference, the two-way statistical Wilcoxon test was used at alevel of 0.05 (p < 0.05). Use of anested UNet architecture reduced the predicted dose MAE in DVH indices. The MAE for planning target volume (PTV), bladder, rectum, and right and left femur were D98% = 1.11 ± 0.90; D98% = 2.27 ± 2.85, Dmean = 0.84 ± 0.62; D98% = 1.47 ± 12.02, Dmean = 0.77 ± 1.59; D2% = 0.65 ± 0.70, Dmean = 0.96 ± 2.82; and D2% = 1.18 ± 6.65, Dmean = 0.44 ± 1.13, respectively. Additionally, the greatest geometric similarity was observed in the mean SSIM for UNet and nested UNet (0.91 vs.0.94, respectively). The nested UNet network can be considered asuitable network due to its ability to improve the accuracy of dose distribution prediction compared to the UNet network in an acceptable time.

Meson mass and width: Deep learning approach

It is fascinating to predict the mass and width of the ordinary and exotic mesons solely based on their quark content and quantum numbers. Such prediction goes beyond conventional methodologies traditionally employed in hadron physics for calculating or estimating these quantities. The relation between the quantum numbers and the properties of the mesons, such as the mass and width, is complicated in the world of particle physics. However, the deep neural network (DNN) as a subfield of machine learning techniques provides a solution to this problem. By analyzing large datasets, deep learning algorithms can automatically identify complex patterns among the particles’ quantum numbers, and their mass and width, that would otherwise require complex calculations. In this study, we present two approaches using the DNNs to estimate the mass of some ordinary and exotic mesons. Also for the first time, the DNNs are trained to predict the width of ordinary and exotic mesons, whose widths have not been experimentally known. Our predictions obtained through the DNNs, will be useful for future experimental searches. Published by the American Physical Society 2024

P403 A new criterion, combining bowel wall thickness and submucosal index (SMI), is useful for estimating endoscopic improvement in Ulcerative Colitis

Abstract Background Endoscopic improvement (EI), Mayo endoscopic subscore of 0 or 1, is considered a therapeutic target in ulcerative colitis (UC) treatment. The potential to estimate EI non-invasively is an advantage of intestinal ultrasound (IUS). In a former study, we developed a new ultrasound parameter, the submucosal index (SMI), calculated as the ratio of the thickness of the submucosa to the thickness of the bowel wall (BWT), and reported that combining BWT and SMI could be a practical criterion for estimating EI without the assessment of bowel wall vascularity using color Doppler evaluation. In the present study, we validated the EI estimation ability of our B-mode-based UC criterion, Kyorin Ultrasound Criterion for UC (KUC-UC; BWT&amp;lt;3.8mm and SMI&amp;lt;50%), using an external cohort. Methods Patients who underwent IUS and CS at Kyorin University Hospital were included. The inclusion criteria were (1) both IUS and endoscopy (sigmoidoscopy or CS) for UC were performed between July 2021 and June 2022, (2) the interval between IUS and endoscopy was within 15 days, and (3) no change or addition of therapeutic agents between the two examinations. IUS findings including BWT, SMI, and modified Limberg score were evaluated. In the modified Limberg score, the threshold of normal BWT was less than 3 mm, while the original Limberg score employed less than 4 mm. Results The KUC-UC criterion defined as BWT &amp;lt; 3.8 mm and SMI &amp;lt; 50.0% is practical because it uses only B-mode findings and does not require complex calculations. We tested the ability of this criterion to estimate EI in UC. A total of 122 colon segments were evaluated by transabdominal IUS and CS. The criteria showed a sensitivity of 67.3%, specificity of 97.1%, PPV of 94.6%, and NPV of 80.0%. In the previous development cohort, the PPV and NPV of KUC-UC were 95.5% and 82.7%, respectively. Based on the above, this validation cohort is considered equivalent to the development cohort. BWT &amp;lt; 3 mm and MUC have been reported as useful criteria for EI estimation. In the present cohort, BWT &amp;lt;3mm showed a sensitivity of 67.3%, specificity of 91.4%, PPV of 85.4%, and NPV of 79.0%, and MUC demonstrated a sensitivity of 75.0%, specificity of 88.6%, PPV of 83.0%, and NPV of 82.0%. These results indicate that KUC-UC has a considerable potential to estimate EI as BWT &amp;lt; 3 mm or MUC. Conclusion External validation showed that KUC-UC, using only B-mode findings without complicated calculations, is feasible, accurate sonographic criteria to estimate the EI of UC. The KUC-UC criterion could be one of the options for estimating EI in UC.

Measuring the quality and accessibility of urban greenery using free data sources: A case study in Bratislava, Slovakia

The importance of assessing urban greenery is growing, especially in the context of global warming and the emergence of urban heat islands. The paper proposes a set of measurements to evaluate the quality and accessibility of greenery based on freely available geographic data: Sentinel-2 satellite images, Urban Atlas, and Open Street Map. The quality (or availability) of urban greenery is derived from Sentinel-2 images by using the spectral Forest Index (FI). The proposed Neighborhood Green Quality Indexes (NGQI0/30, NGQI350) evaluate greenery in the near and far surroundings of the spatial unit by averaging the FI values. The Accessibility to Green Space Index (AGSI) measures accessibility to green spaces (GS) based on the number of theoretical functional levels within reach and the average normalised distance to the nearest GS across levels. We also propose to separately assess accessibility to parks with amenities through the Accessibility to Urban Parks Index (AUPI). Such areas attract specific groups of the population, such as elderly people and mothers with children, who are among the most vulnerable during heat waves. The proposed set of measurements can be applied to a square grid and to buildings. A mutual comparison of the proposed measurements in Bratislava, the capital of Slovakia, confirmed that each measurement captures different characteristics of urban greenery. The comparison of FI with two other widely used green quality indicators showed that FI achieves the highest correlation with the land surface temperature during hot summer days. When evaluating the precision of the NGQI0/30 calculation, Sentinel-2-derived FI proved to be a sufficient substitute for high-resolution urban greenery data sources. Since the proposed measurements do not require complex calculations and hard-to-obtain data, they are easily applicable to other cities.

A method to manufacture spiral bevel gears by equivalent completing

As a transmission part for industrial application the manufacture of spiral bevel gear is particularly important. The present machining methods for manufacturing spiral bevel gears, including the so called five-cut method and completing method, have drawbacks such as low processing efficiency, requiring complex calculations and high requirements on the machine-tool performance, respectively. To solve the above problems, an equivalent completing method is proposed to process spiral bevel gear in this paper. Firstly the machine setting parameters by completing were translated from the Cradle-type hypoid generator to Cartesian-type hypoid generator and the workpiece is swing during process. CNC motion axes expression of Cartesian-type hypoid generator were expressed as sixth-order polynomial, the influences of coefficient on the tooth surface topology were researched. Then the method to machine spiral bevel gear was put forward by reducing the swing axis of workpiece, obviously a deviation of tooth surface was caused between theoretical and axis-reduced. As a response, a flank correction model was established and the other polynomial coefficients were adjusted to eliminate the deviation. Finally simulation and cutting experiment were carried out by a numerical example. The experimental results show that the proposed method is effective and feasible. The method proposed in this paper overcome and enrich the disadvantages of existing manufacture methods of spiral bevel gear.

МОДЕЛИРОВАНИЕ СГЛАЖИВАЮЩИХ ТРАЕКТОРИЙ ПЕРЕМЕЩЕНИЯ АВТОНОМНЫХ ЭЛЕКТРИФИЦИРОВАННЫХ ПЛАТФОРМ

Automation of cargo transportation both inside production and warehouse premises and between individual objects of livestock and crop production complexes is a promising direction in saving fuel and energy resources of the agro-industrial complex. The use of autonomous vehicles for these purposes, including electrified platforms with non-operational adaptive control, is especially necessary due to the movement of significant volumes of cargo in cramped conditions of buildings and structures. However, the use of broken lines in the planning of ATU movements leads to the need for a significant reduction in the movement speed during the passage of turning sections of the trajectory. This significantly increases the execution time of technological operations, leads to additional energy consumption for braking and acceleration. Thus, the approach proposed in the work to the analytical determination of smoothing movement trajectories of autonomous vehicles is relevant. (Research Purpose) The research purpose is developing an approach to the construction of smoothing sections of the trajectory of a non-operational vehicle with adaptive control that does not require solving optimization problems. (Materials and methods) For a smoothing curve of polynomial form, a system of equations is derived from geometric conditions that defines its most rational form from the point of view of the maximum speed of passing an obstacle. After its representation in the local coordinate system associated with the bypassed obstacle, the equation of the desired curve is found. For the practical implementation of the method, formulas for the transition from a local coordinate system to an absolute one are given. (Results and discussion) A general method is proposed for smoothing the reference broken trajectories obtained at the initial stage of planning the movement of an autonomous electrified platform in cramped conditions. In the local coordinate system associated with the obstacle, the shape of the smoothing transition curves is found and formulas for the transition to the absolute coordinate system are given. (Conclusions) The obtained analytical solution to the construction of smoothing sections of the trajectory of an autonomous vehicle in cramped conditions of buildings and structures for agricultural purposes does not require complex calculations. This simplifies its practical application, including the implementation of programmable adaptive control systems using microprocessor hardware.

Influence of cut parameters on mesh performance of spiral bevel gear by duplex spread blade method

Spiral bevel gears are key components in many mechanical transmission systems, and their production is always of great interest to industry, and hence, subjected to intensive research widely. The present machining methods for manufacturing spiral bevel gears, including the so called five-cut method and completing method, have drawbacks such as low processing efficiency, requiring complex calculations and high requirements on the machine-tool performance, respectively. To solve the above problems, the duplex spread blade method is proposed. Firstly, geometric parameters and machine setting parameters were comprehensively considered, and then a modified reference point was selected to deduce the machine setting parameters. Tooth contact analysis (TCA) model considering misalignment was established to check meshing performance, the influence of cutter parameters and misalignment on meshing performance was studied. As the research reveals that the cutter radius has an effect on the bias of contact trace, cutter number has an impact on the position of contact pattern. The experimental results are consistent with the theoretical which verified the effectiveness and feasibility of the proposed method. The results of this paper have a guiding significance and enrich the machining method for spiral bevel gear.

Efficient approximate analytical technique to solve nonlinear coupled Jaulent–Miodek system within a time-fractional order

&lt;abstract&gt;&lt;p&gt;In this article, we considered the nonlinear time-fractional Jaulent–Miodek model (FJMM), which is applied to modeling many applications in basic sciences and engineering, especially physical phenomena such as plasma physics, fluid dynamics, electromagnetic waves in nonlinear media, and many other applications. The Caputo fractional derivative (CFD) was applied to express the fractional operator in the mathematical formalism of the FJMM. We implemented the modified generalized Mittag-Leffler method (MGMLFM) to show the analytical approximate solution of FJMM, which is represented by a set of coupled nonlinear fractional partial differential equations (FPDEs) with suitable initial conditions. The suggested method produced convergent series solutions with easily computable components. To demonstrate the accuracy and efficiency of the MGMLFM, a comparison was made between the solutions obtained by MGMLFM and the known exact solutions in some tables. Also, the absolute error was compared with the absolute error provided by some of the other famous methods found in the literature. Our findings confirmed that the presented method is easy, simple, reliable, competitive, and did not require complex calculations. Thus, it can be extensively applied to solve more linear and nonlinear FPDEs that have applications in various areas such as mathematics, engineering, and physics.&lt;/p&gt;&lt;/abstract&gt;

Nonlinear Controller for an Inverted Pendulum Using the Trigonometric Function

In this paper, a nonlinear controller (TR) for an inverted pendulum using the trigonometric function is presented. The TR controller is a new proposal, which is represented by a simple mathematical formula. TR operation does not require complex calculations, so it can be applied even to the simplest microcontrollers. Tuning the TR controller is very simple, and the range of stable operation is very wide. Simulation tests of the TR controller showed that the controller is effective even for deviations exceeding 50∘. The TR controller tests were compared to the results of a PID controller. The TR controller is designed to stabilise an inverted pendulum in the equilibrium point, a state in which the pendulum is in a upright position. Stabilisation for other deflection-angle set points was not taken into account. During the research, steps were taken to simulate phenomena characteristic of real solutions. An inertial block and a disturbance were introduced into the test system. Despite the introduced difficulties, the TR controller effectively stabilised the pendulum without the need to retune the controller settings. Consequently, the TR controller is an attractive alternative to previously applied solutions for the stabilisation of an inverted pendulum.

Topographic Correlation of Microperimetry With Structural Characteristics in Diabetic Macular Ischemia

This study aimed to determine the threshold for defining abnormal retinal sensitivity (RS) that correlates with structural changes in diabetic macular ischemia (DMI) patients with stable treated proliferative diabetic retinopathy (PDR). Prospective cross-sectional study. In a single center, we recruited 85 eyes (67 patients) with stable treated PDR with best-corrected visual acuity (BCVA) ≥54 Early Treatment Diabetic Retinopathy Study (ETDRS) letters (Snellen equivalent 20/80) and optical coherence tomography angiography evidence of DMI. The function-function and function-structure correlation were assessed. Two preselected thresholds in overall RS (oRS), 25 decibels (dB) and age-matched normative data (AMND), were tested on their ability to reflect abnormal anatomy in DMI. Finally, a multivariable regression model was established to depict the relationship between the oRS and various parameters. The oRS showed only a modest correlation with BCVA and low-luminance visual acuity (LLVA). The whole-image deep vessel density (wiDVD) was the most reliable vascular metric correlated with RS. For every 1% decline in the wiDVD, the oRS decreased by 0.37 dB (P < .001) after multivariable adjustment. Furthermore, both a reduction of oRS to <25 dB or below AMND could differentiate eyes with FAZ ≥0.5 mm2, whole image superficial vessel density (wiSVD) <37.7%, wiDVD <41.9%, and the presence of disorganization of the retinal inner layers (DRIL) from their counterparts. The absolute value of 25 dB in oRS is worth considering as a trial endpoint, because it does not require complex calculation and closely reflects the structural abnormalities in DMI.

Tuning of controller parameters using Pythagorean fuzzy similarity measure for stable and time delayed unstable plants.

This paper proposes a tuning method based on the Pythagorean fuzzy similarity measure and multi-criteria decision-making to determine the most suitable controller parameters for Fractional-order Proportional Integral Derivative (FOPID) and Integer-order Proportional Integral-Proportional Derivative (PI-PD) controllers. Due to the power of the Pythagorean fuzzy approach to evaluate a phenomenon with two memberships known as membership and non-membership, a multi-objective cost function based on the Pythagorean similarity measure is defined. The transient and steady-state properties of the system output were used for the multi-objective cost function. Thus, the determination of the controller parameters was considered a multi-criteria decision-making problem. Ant colony optimization for continuous domains (ACOR) and artificial bee colony (ABC) optimization are utilized to minimize multi-objective cost functions. The proposed method in the study was applied to three different systems: a second-order non-minimum phase stable system, a first-order unstable system with time delay, and a fractional-order unstable system with time delay, to validate its effectiveness. The cost function utilized in the proposed method is compared with the performance measures widely used in the literature based on the integral of the error, such as IAE (Integral Absolute Error), ITAE (Integral Time Absolute Error), ISE (Integral Square Error), and ITSE (Integral Time Square Error). The proposed method provides a more effective control performance by improving the system response characteristics compared to other cost functions. With the proposed method, the undershoot rate could be significantly reduced in the non-minimum phase system. In the other two systems, significant improvements were achieved compared to other methods by reducing the overshoot rate and oscillation. The proposed method does not require knowing the mathematical model of the system and offers a solution that does not require complex calculations. The proposed method can be used alone. Or it can be used as a second and fine-tuning method after a tuning process.

Investigating the Path Tracking Algorithm Based on BP Neural Network.

In this paper, we propose an adaptive path tracking algorithm based on the BP (back propagation) neural network to increase the performance of vehicle path tracking in different paths. Specifically, based on the kinematic model of the vehicle, the front wheel steering angle of the vehicle was derived with the PP (Pure Pursuit) algorithm, and related parameters affecting path tracking accuracy were analyzed. In the next step, BP neural networks were introduced and vehicle speed, radius of path curvature, and lateral error were used as inputs to train models. The output of the model was used as the control coefficient of the PP algorithm to improve the accuracy of the calculation of the front wheel steering angle, which is referred to as the BP-PP algorithm in this paper. As a final step, simulation experiments and real vehicle experiments are performed to verify the algorithm's performance. Simulation experiments show that compared with the traditional path tracking algorithm, the average tracking error of BP-PP algorithm is reduced by 0.025 m when traveling at a speed of 3 m/s on a straight path, and the average tracking error is reduced by 0.27 m, 0.42 m, and 0.67 m, respectively, at a speed of 1.5 m/s with a curvature radius of 6.8 m, 5.5 m, and 4.5 m, respectively. In the real vehicle experiment, an electric patrol vehicle with an autonomous tracking function was used as the experimental platform. The average tracking error was reduced by 0.1 m and 0.086 m on a rectangular road and a large curvature road, respectively. Experimental results show that the proposed algorithm performs well in both simulation and actual scenarios, improves the accuracy of path tracking, and enhances the robustness of the system. Moreover, facing paths with changes in road curvature, the BP-PP algorithm achieved significant improvement and demonstrated great robustness. In conclusion, the proposed BP-PP algorithm reduced the interference of nonlinear factors on the system and did not require complex calculations. Furthermore, the proposed algorithm has been applied to the autonomous driving patrol vehicle in the park and achieved good results.

Flocking and formation control for a group of nonholonomic wheeled mobile robots

The problem of flocking and formation of a group of nonholonomic wheeled mobile robot is addressed in this paper. Based on the cascade structure of the kinematic model, two kinematic controllers are proposed to achieve formation and flocking behaviors. The proposed control laws present a P and PI-like structure plus a feedforward term and do not require complex calculations. The interaction between the robots is modeled using graph theory. The performance of the proposed control laws is validated by experimental tests on a group of four differential-drive wheeled mobile robots.

Finite-time lag projective synchronization of delayed fractional-order quaternion-valued neural networks with parameter uncertainties

This paper discusses a class issue of finite-time lag projective synchronization (FTLPS) of delayed fractional-order quaternion-valued neural networks (FOQVNNs) with parameter uncertainties, which is solved by a non-decomposition method. Firstly, a new delayed FOQVNNs model with uncertain parameters is designed. Secondly, two types of feedback controller and adaptive controller without sign functions are designed in the quaternion domain. Based on the Lyapunov analysis method, the non-decomposition method is applied to replace the decomposition method that requires complex calculations, combined with some quaternion inequality techniques, to accurately estimate the settling time of FTLPS. Finally, the correctness of the obtained theoretical results is testified by a numerical simulation example.

Разработка алгоритма выявления вредоносных программ для платформы Android путем проведения анализа файла манифеста

The available algorithms for detecting malicious software are often not enough to detect new types of viruses. In this regard, the issues related to the use of reverse engineering of malicious software codes intended for the Android operating system are considered. It is proposed to conduct a comprehensive analysis of the code and manifest of the mobile application in order to form the attributes of malicious software and create detection algorithms for a specific operating system. Research objective: to show the relevance of reverse engineering and to develop a heuristic analysis algorithm that allows detecting the presence of hidden malicious code in mobile applications by analyzing code metadata. Methods: the article uses the reverse engineering method on the example of actual Trojans to form attributes that characterize the possibility of hidden malicious code in a mobile application, according to the logical values of which the algorithm makes a cumulative decision about the possibility of hidden malicious load. Results: the proposed approach was tested using the VirusTotal database to evaluate errors of the first and second kind and showed 78% efficiency in detecting malicious software only from code metadata using the proposed attributes, does not require complex calculations and time-consuming costs and can be the basis for using artificial intelligence in combination with static and dynamic analysis to identify viruses of the Android operating system. Practical significance: the developed algorithm can be used as an additional element in the integrated antivirus protection system of a smartphone against malware infection.

Prognostic model of the absence of larynx motility recovery in unilateral lesions of the recurrent laryngeal nerve in thyroid surgery

One of the most serious complications in thyroid surgery is damage to the recurrent laryngeal nerve, which can significantly worsen the patient’s quality of life, so predicting the course of the disease is very important, as it contributes to timely and targeted aid to patients and the determination of optimal treatment tactics.&#x0D; Objective — construction of the prognostic model of the absence of larynx motility recovery in unilateral lesions of the recurrent laryngeal nerve in thyroid surgery&#x0D; Materials and methods. In the years 2018 — 2021, a prospective single‑center study was conducted at the Ukrainian Scientific and Practical Center of Endocrine Surgery, Transplantation of Endocrine Organs and Tissues of the Ministry of Health of Ukraine. Investigation involved 164 patients after thyroidectomy with unilateral motility disorder of the larynx. The investigated patients are divided into two groups: the main group (n = 33) included patients with unilateral paralysis of larynx (the mean age 49.7 ± 11.1 years), and control group consisted of 131 patients with unilateral paresis of larynx (the mean age 43.2 ± 14.6 years).&#x0D; Results. Prognostication of disease was conducted by means of three methodologies. The method of statistical analysis of Wald was conducted taking into account the most meaningful informing laryngoscopy signs with their gradations (9 laryngoscopy signs and 1 sign that is related to age), that were distinguished by us in previous prognostic research. Diagnostic coefficients and information measures of Kullback J of selected features were determined and a special template was developed using the MS Excel program to automate diagnostic analysis. Method of binary logistic regression allows the expectation of dependence of binary initial variable (present/absent paralysis) after influence of factor variables. Three factor signs that remained after recalculation have been investigated. To ensure quick and convenient execution of calculations, a corresponding template has also been created in the MS Excel program. The prognostic express test, which enabled us to build an easy‑to‑use test based on the most significant two predictors and their gradations, which were converted into ranks. A comparison of the occurrence of paresis/paralysis of the larynx was made for different sums of ranks.&#x0D; Conclusions. The diagnostic method based on the sequential Wald analysis, despite good performance in the case of a definite result, gave about 25 % indeterminate results and therefore needs further improvement based on a more representative sample. The diagnostic model built using binary logistic regression led to good results, but working with it requires a personal computer and an appropriate template for calculations in the Excel program. The prognostic express test, which is based on the consideration of only two predictors, is convenient, does not require complex calculations and provides an acceptable level of sensitivity and specificity, which can be widely used in the clinical practice of first‑line otorhinolaryngologists for a timely decision on further conservative or surgical treatment.&#x0D;

ПОЛЬОВІ МЕТОДИ АРХЕОЛОГІЧНОЇ ГЕОФІЗИКИ У СВІТІ ТА В УКРАЇНІ: ВИТОКИ, СТАНОВЛЕННЯ, СУЧАСНІСТЬ

The article describes the history of the development of geophysical methods in archaeological studies in Europe, the USA, the former USSR and Ukraine. In the 1950s the researchers quickly proceeded from the first sampling to the mass magnetic and electric measurements. In the 1980s there was a transition to digital registration during field studies, as well as rapid development of data processing. This led to the introduction of some geophysical methods in archaeology, which require complex calculations when processing the signal and inversion of data, such as georadar method, electrical resistivity tomography, induction method, etc. At the current stage, there is a need to interpret these more and more detailed and largescale geophysical data in the context of the differentiation of more and more weak in contrast physical properties, and small-scale inhomogeneities in the soil cover. Confirmation of the anthropogenic and technogenic occurrence of geophysical anomalies is searched for using direct measurement and modeling of physical parameters of soil and archaeological materials. The work also presents the achievements of domestic geophysicists, as they became the basis for the great modern archeological projects and made the archeological geophysics the fundamental part of the cultural heritage research in Ukraine.

Modeling of information transmission systems in modern mobile terms

The work is dedicated to information transmission systems in modern mobile networks. The main task of any information transmission system is to combat various kinds of interference which lead to distortion or complete information loss and thus reduced communication channel reliability. Therefore, it became necessary to develop adaptive data transmission systems, in which adaptive methods help to achieve high-quality control in the absence of sufficiently complete a priori information about the characteristics of the controlled process or under conditions of uncertainty. The research was carried out on a simulation model of data transmission built on the basis of binary symmetry. The proposed adaptive system is based on the assessment of the state of the data transmission channel, according to which the bit rate of the transmitted data and the parameters of the noise-correcting code are selected, which provides a certain level of errors on the receiving side, taking into account the limited bandwidth of the communication channel. The developed simulation model of adaptation to the state of the communication channel demonstrates the required level of reliability and allows to work with different levels of noise in the communication channels, and the occurrence of an error in the channel can be either uniform during data transmission or random. The results of simulation modeling testify to the correctness of the proposed solution and allow the evaluation the main parameters of information transmission systems in mobile networks. The proposed model of information transmission with adaptation to the state of the communication channel may be applied in modern mobile networks, telecommunications and computer systems with an increased level of quality requirements for information transmitted at low speed, since the proposed solution does not require complex calculations.

Virtual Current Coefficients Based Power Transistors Fault Diagnosis for Small Power EV-SRM Drives

Implementation of fault diagnosis for power converter is critical to improve the reliability of electric vehicle (EV) with switched reluctance motor (SRM) drive. Conventional fault diagnosis methods are usually suitable for a single chopping mode or a certain control strategy. To avoid the problem, a virtual current coefficient-based diagnosis method for power transistors is proposed considering different chopping modes, control strategies, and fault cases simultaneously. The multipoint current detection method is proposed to obtain more current information, which is capable of providing remarkable fault features. The sensor current variations under various fault conditions are analyzed. The fault is first detected by identifying the error between the real sensor current and the value calculated with the mixed logic model. Three virtual current coefficients are introduced to obtain the fault location principles. The fault types and fault power transistors are recognized according to the difference between the real current coefficients and the virtual current coefficients. The applications of the fault diagnosis method are extended with the proposed scheme. The method does not require complex calculation, and thus has a good dynamic performance. Experiments on a three-phase 12/8 SRM drive validate the effectiveness of the proposed fault diagnosis method.

Geometric approach to the solution of the Dubins car problem in the formation of program trajectories

The paper considers an approach to the formation of control program trajectories of moving objects (UAVs, ships) as a solution to the optimal problem in terms of Dubins path search. Instead of directly solving the Pontryagin’s maximum principle, it is proposed to use a simple analysis of possible control strategies in order to determine among them the optimal one in terms of time spent on a trajectory. The problem of finding the shortest trajectory of movement of an object from one point to another is solved, and for both points their coordinates and heading angles at these points are given, as well as three absolute values of the circulation radii corresponding to the given control signals on each of the three sections of the trajectory. The problem of finding the Dubins curves is reduced to determining the parameters of two intermediate points at which the control changes. All possible directions of control change options are considered, taking into account the existing constraints, also the lengths of the corresponding motion trajectories are calculated, and the optimal one is selected. The problem of constructing a trajectory is solved as well, which ensures a smooth conjugation of two linear fragments of trajectories and passes through the point of their intersection. The solution of the optimal trajectory problem using the Dubins car gives a single trajectory. In contrast to this, the proposed method considers several trajectories admissible by the constraints, from which the optimal one is selected by exhaustive search. The presence of several feasible strategies gives advantages for each specific situation of choosing a trajectory depending on the environment. Instead of directly solving the Pontryagin’s maximum principle and constructing a three-dimensional optimal trajectory, the authors used a simple analysis of possible control strategies in order to determine among them the optimal one in terms of elapsed time. The approach was motivated by the limited number of possible control strategies for Dubins paths, as well as the simplicity of analytical calculations for each of them, which allows performing these calculations in real time. The high speed of calculations for the problem of determining the optimal trajectory is due to the fact that the proposed method does not require complex calculations to solve the problem of nonlinear optimization, which follows from the Pontryagin’s principle.